In cyclically movable or reciprocating linkages used in machinery, automobiles and the like, because of unavoidable manufacturing tolerances and unpredictable non-homogeneity of materials, vibration cannot be removed by system or machinery design alone. Rather each equipment will need be fully force balanced by proper positioning of counterweights.
However, such positioning has in the past been confined mostly to rotating members in which the counterweights are all attached to a single shaft. Balancing of automobile tires mounted on a wheel for rotation about the wheel axle, is an example. The complexity of the parameters involved in balancing of a four bar or n-bar linkage reciprocating in a single plane by determination of the required correction masses and positioning to balance shaking force components kinematically has in the past prevented adoption of any general process or solution.
The general principles and problems of vibration in such reciprocating objects as connecting rods for automobile engines representative of the state of the art are set forth in U.S. Pat. No. 2,282,052--H. O. Hem--May 5, 1942. Thus, a static balance is attained by comparison with a master rod in a mechanism indicating weights at two end bearing regions of the connecting rod and permitting a weight calibration necessary to attain balance.
Dynamic balancing machines have been proposed such as set forth in U.S. Pat. No. 3,751,987--B. E. Whitmore--Aug. 14, 1973. Electric balancing techniques provide a cathode ray polar coordinate plan position display. Magnetic or optical transducers are used at bearings to derive signals from a workpiece rotating thereon. Thus, the size of a correction mass, the radius from center and angle may be derived.
U.S. Pat. No. 3,077,781--S. H. Silver--Feb. 19, 1963 describes a dynamic balance system operable to detect and correct balance in two axially separable planes of a rotor rotated in bearings which permit vibration in a plane including the rotor axis.
Other piston or connecting rod balance testing machines are represented by U.S. Pat. Nos. 1,746,352--H. O. Hem--Feb. 11, 1930 and 1,908,786--W. F. Pioch--May 16, 1933.
None of these systems, however, can balance a complex interconnected n-bar cyclically reciprocating mechanism.
It is therefore a general objective of this invention to provide techniques for force balancing of machines or linkage sub-assemblies thereof having interconnected n-bar planar linkages.
Other objects, features and advantages of this invention will be found throughout the following description, drawings and claims.